water chem/co2

[mooman]

Water chem question. I had a customer at the LFS I work at tell me that his water params were gh=6 kh=5 and ph=6.0 (adjusted using peat and blackwater extract). The question the customer was asking was in relation to the CO2 content of his tank (if his parameters were correct then his co2 levels should have been off the chart, no?) He does not use co2 injection, but does have some surface aggitation. From my understanding of water chem this is not possible, is it?

Does the chart refer to actual co2 levels or just potential co2 levels if surface is not aggitated?
Is this just a case of him testing incorrectly?
Have I totally confused you all yet?

 

[Left C]

Peat throws the CO2/KH/pH chart off, I'm told. Why?

 

[RTR]

The pH/KH/CO2 tables assume that there are no acids present which would affect the relationship other tha the carbonic acid from the dissolved CO2. Peat releases many tannins and tannic acid, Blackwater extract is little but those acids. When either or both is present, the tables or the pH/CO2 relationships do not apply.